Jama
Class Matrix

The Java Matrix Class provides the fundamental operations of numerical
linear algebra. Various constructors create Matrices from two dimensional
arrays of double precision floating point numbers. Various "gets" and
"sets" provide access to submatrices and matrix elements. Several methods
implement basic matrix arithmetic, including matrix addition and
multiplication, matrix norms, and element-by-element array operations.
Methods for reading and printing matrices are also included. All the
operations in this version of the Matrix Class involve real matrices.
Complex matrices may be handled in a future version.

Five fundamental matrix decompositions, which consist of pairs or triples
of matrices, permutation vectors, and the like, produce results in five
decomposition classes. These decompositions are accessed by the Matrix
class to compute solutions of simultaneous linear equations, determinants,
inverses and other matrix functions. The five decompositions are:

Cholesky Decomposition of symmetric, positive definite matrices.

LU Decomposition of rectangular matrices.

QR Decomposition of rectangular matrices.

Singular Value Decomposition of rectangular matrices.

Eigenvalue Decomposition of both symmetric and nonsymmetric square matrices.

Example of use:

Solve a linear system A x = b and compute the residual norm, ||b - A x||.

print

Print the matrix to stdout. Line the elements up in columns.
Use the format object, and right justify within columns of width
characters.
Note that is the matrix is to be read back in, you probably will want
to use a NumberFormat that is set to US Locale.

print

Print the matrix to the output stream. Line the elements up in columns.
Use the format object, and right justify within columns of width
characters.
Note that is the matrix is to be read back in, you probably will want
to use a NumberFormat that is set to US Locale.

read

Read a matrix from a stream. The format is the same the print method,
so printed matrices can be read back in (provided they were printed using
US Locale). Elements are separated by
whitespace, all the elements for each row appear on a single line,
the last row is followed by a blank line.